In marine seismic exploration a seismic source emits sound waves which are reflected/refracted by interfaces between layers of the subsurface with different elastic properties. The amplitudes and arrival times of the returned sound waves are recorded by seismic sensors. Two main techniques are used to record the returned sound wave signals, one is by using hydrophone cables that are towed behind a vessel near the sea level, the other is to deploy seismic nodes at the ocean bottom. This invention relates to the latter technique.
After the seismic data has been recorded by the seismic nodes at the sea bottom, the seismic nodes are retrieved for transferring the seismic data to a data storage unit.
U.S. Pat. No. 8,050,140 discloses a system for collecting seismic data in marine environments by deploying multiple, continuous operating, wireless, self-contained ocean bottom sensor units or pods. The pods are attached to one another utilizing a flexible, non-rigid, non-conducting cable that is used to control deployment of the pods through the water. The pods are deployed and retrieved from the uniquely configured deck of a marine vessel, wherein the deck is provided with a conveyor system and a handling system to attach and detach individual pods from the non-rigid cable. In one embodiment, as part of the deck configuration, the individual pods are randomly stored in juke box fashion in slotted racks. When seated within the slot of a rack, the seismic data previously recorded by the pod can be retrieved and the pod can be charged, tested, re-synchronized, and operation can be re-initiated without the need to open the pod.
In the system of U.S. Pat. No. 8,050,140 and similar systems the seismic nodes or pods are stored in racks at the deck of the deploying/retrieving vessel. This takes up a lot of space and limits the number of seismic nodes that can be deployed at the sea bottom by the vessel.
To enable a vessel for deploying/retrieving seismic nodes to cover a larger area, and thereby reduce the cost for seismic exploration, there is a need for a technical solution that enables storing of a large number of seismic nodes at the deck of the deploying/retrieving vessel. The purpose of the invention is to provide this technical solution.